Refrigeration apparatus and method



Dec, 14, 1943. P. SCHLUMBOHM REFRIGERATION APPARATUS AND METHbD Filed Feb. 29, 1940 INVENTOR Patented Dec. 14, 1943.

UNITED STATES PATENT OFFICE 2,336,641 REFRIGERATION APPARATUS AND METHQD Peter Schlumbohm, New York, N. Y., assignor to Propane Development Corporation, New York, N. Y., a corporation of Delaware Application February 29, 1940, Serial No. 321,563

11 Claims.

there was a great tendency for the formation of,

a mass of oil and refrigerant bubbles or foam in the crankcase of the compressor with accompanying disadvantages such as loss of efficiency due to oil carried over into the evaporator which retards heat transfer and-increased wear of moving parts due to abnormal oiling conditions. The presence of foam in the crankcase tends to obstruct the pil passages within the compressor which are connected to the crankcase and the reflux passage which may comprise a bored channel leading from the compressor intake and passing through the walls of the cylinders down into the crankcase. Another disadvantage of the presence of foam lies in the fact that breathing in the crankcase due to cyclical change of temperature causes foam to carry oil from the crankcase to the compressor head, to the valves including the intake valves, and in general effects an undesirable passage of oil through the circuit. Prior attempts to prevent undesirable circulation of oil have involved the use of baflles and oil separators, but such constructions have not been entirely successful in the retardation of foam formation, particularly when one of the class of hydrocarbons mentioned above is the medium being pumped. While some prior constructions have shown thermal affecting means associated with the oil bath of compressor crankcases to maintain the same at predetermined lubricating temperatures, such means are incapable of retarding and preventing foam formation and -are generally incomparable with "the instant invention.

It is an object of the instant invention to provide a novel and efficient arrangement for retarding and preventing the formation of foam in the oil reservoirs of the crankcases of compressors in pumping and compression refrigeration systems wherein hydrocarbonv gases like propane, butane and dichlorodifluoromethane are being pumped.

It is a further object of the instant invention to provide a thermodynamically. efficient, in-

expensive, refrigeration heat exchange means associated with the oil reservoir or crankcase of a compressor.

It is still another object of the instant invention to teach a novel method for the retardation and prevention of undesirable oil circulation in pumping and compression refrigeration systems.

Other objects and the nature and advantages of the invention will be apparent from the fol- ,lowing description taken in conjunction with the accompanying drawing, wherein:

Fig. 1 is a view in elevation with parts broken away and parts shown in section of a portion of a refrigerating system, including a compressor,

in accordance with the instant invention;

Fig. 2 is a horizontal section taken along line 2--2 of Fig. 1, looking in the direction of the arrows, showing the lower portion of the compressor crankcase and the cooling coil therewithin;

Fig. 3 is a fragmentary elevational' view with parts broken away and parts shown in section of but of a modipressor It! includes a crankcase II which is supported on a base l2. The moving parts of the compressor "are driven by any motive means such as an electricmotor or combustion engine, and the drive between said motive means and said compressor may include the combined compressor flywheel and pulley I'S'and the endless belt I. The compressor crankcase ll may include an oil level sight glass l6 and be secured to the compressor cylinder by the utilization of integral flanges and bolts l5. Refrigerant gas which may be a hydrocarbon such as propane, butane, dichlorodifluoromethane and the like is discharged from the compressor and passed too.

shaped heat absorbing coil is which may be located directly within the oil bath within the compressor crankcase ii. The discharge side of the coil it where it emerges from the crankcase Ii is connected to the conduit i8 which leads to the suction side of the compressor Ill. The relatively cold gases, sub-atmospheric in temperature, and any liquid refrigerant which may be entrained therein, passing through the heat absorbing coil I9, will serve to maintain the temperature of the oil bath at such a low temperature level as to retard and substantially prevent deleterious foam formation in the crankcase of the compressor wherein the lubricating oil is housed.

Referring to Figs. 3 and 4 wherein is shown a modified form of the invention, the heat absorbing elements are located exteriorly of the compressor crankcase Ii, and the arrangements are such'that a novel and ingenious countercurrent and convection current thermal transfer takes place in order to'effect the cooling of the oil bath in the compressor crankcase to such a low temperature level as to retard and substantially prevent the formation of foam therewithin. The compressor crankcase II is provided with an upper connection lid and a lower connection I la respectively with the inclined housing Iii which is generally tubular in configuration. closed at its outer ends, larger in diameter, and concentric with the inner tube 2i which connects the conduit li leading from the evaporator with the conduit l8 leading to the suction side of the compressor. The relatively cold fluid leaving the evaporator will be passed through the tube 2!, which is inclined with respect to the horizontal, and absorb heat from the oil surrounding it. The cooled oil will continually pass downwardly through the outer cylinder 20 to the connection "a and the relatively warm oil from the crankcase II will be continually passed to the outer cylinder 20 through'the high connection Ma. and a convection current will be thereby set up. This convection current of oil will be in counterflow relation to the passage of cold refrigerant fluid through the tube 2i to effect an efficient thermal exchange which will retard and substantially prevent the formation of foam in the oil reservoir within the crankcase ii. I

The embodiment illustrated in Fig. differs from that shown inand described in connection with Figs. 3 and 4 by the addition of a pump in the oil circuit which effects the passage of oil from the crankcase of the compressor through the oil cooling means which is located exteriorly of the compressor. The crankcase ii, at a level below the level of oil therein, is connected to the gear pump 24 by a conduit 28. The discharge side of the gear pump is connected to the upper end of the inclined Jacket 20 by the conduit 2i and the lower portionof the Jacket is connected to the crankcase ii by the conduit 22 which may be at the same level at which the conthe same general contours as the compressor crankcase i i to thereby provide a cooling space 21a with which the conduit ll leading from the evaporator may be connected at a high level and the conduit i8 leading to the suction side of the compressor may be connected at a low level to effect a countercurrent flow of cooling fluid around and about the relatively thin walled receptacle 21 which serves as an oil reservoir. As the pressure within the crankcase and the pressure within the space 21a is substantially the same, the walls of the receptacle 21 may be relatively thin and inexpensive and yet thereby be more efficient as a heat transfer element. The receptacle 2! may be conveniently mounted and supported within the crankcase by arranging its flanged upper end 28 between the flanges 28 and 30 of the compressor which may be secured by the bolts l5.-

While the embodiment of the invention shown in Figs. 1 and 2 serves to effect the purpose above set forth, the modifications shown in Figs. 3, 4 and 5 may be utilized to effect a similar purpose in connection with compressors of such configuration a to make impractical theinsertion of a cooling coil or heat exchanger directly within the crankcase. Though the arrangements in these modifications are such that counterfiow takes place, it is to be understood that the connections may be reversed or otherwise modified to effect parallel flow of the medium being pumped and the oil when such is desired.

In the embodiment illustrated in Figs. 6 and 7, in order that the space 21a notfunction as an oil trap, it is preferred that the suction line ll be connected to the lowermost part of the space 21a, and it is definitely advantageous to connect the conduit i1 leading from the evaporator at a higher level and at a location which is horizontaliy disposed from the connection of the conduit It to the space 21a.

It has been found in practice that-the passing of relatively cold. fluids discharged from the evaporator in heat exchange relation with the compressor lubricating oil, as described above, serves to retard and substantially prevent the formation of foam within the oil reservoir of the compressor, particularly when refrigerants of the .type that are miscible with or soluble in the lubricating oil are the mediums being pumped. In practice lubricating oils of a viscosity corresponding to #20 have been utilized in the instant invention and found to be satisfactory. The viscosity'of the oil utilized may be related to the refrigerant fluid thermally associated therewith.

It will be obvious to those skilled in the art that various changes may-be made in this device without departing from the spirit of thc invention, and therefore the invention i not limited to what is shown in the drawing and described in the specification but only as indicated in the appended claims.

2. In a refrigeration system utilizing a hydrocarbon refrigerant, a, compressor, a condenser and an evaporator, means for connecting said elements in a closed circuit including closed conduit means leading from said evaporator to the suction side of said compressor, an oil bath associated with said compressor, mean for thermally associating said closed conduit means leading from the discharge side of said evaporator to the Su ti n Side of said compressor with said oil bath in order to retard and substantially prevent the formation of foam in said oil bath.

3. The process of refrigeration comprising the steps of compressing a hydrocarbon refrigerant, utilizing a. lubricant to aid in the said compression, condensing the refrigerant, evaporating the refrigerant to produce cooling, passing the relatively cold fluid discharged from the evaporator in thermal association with a portion of said lubricant in a manner to effect a thermal convection current of said lubricant in a closed circuit including the passage of at least a portion of said lubricant to a place removed from a' main body thereof where it may be cooled by said thermal association and the return of said cooled lubricant to said main body.

4. The process of refrigeration comprising the steps of compressing a hydrocarbon refrigerant,

utilizing a lubricant to aid in the said compression, condensing the refrigerant, evaporating refrigerant to produce cooling, passing the rela- .tively cold fluid discharged from the evaporator to the place of compression where it may be recompressed, passing a portion of said lubricant from a relatively high level in counterfiow relation and downwardly in thermal association with said discharged refrigerant to cool the same, and i'etulrning said cooled lubricant at a relatively low eve 5. In a refrigeration system utilizing a hydrocarbon refrigerant, a compressor, a condenser and an evaporator, means for connecting said elements in a closed circuit including conduit means leading from said evaporator to the suction side of said compressor, an oil bath associated with said compressor, a portion of said conduit means including a heat exchange element of sufficient capacity to maintain said oil at or below a relatively low temperature level, said heat exchange element being located within said oil bath whereby said oil bath may be sufficiently cooled to retard and substantially prevent the formation of foam therewithin.

6. In a refrigeration system utilizing a hydrocarbon refrigerant, a compressor, a condenser and an evaporator, means for connecting said elements in a closed circuit including conduit means leading from said evaporator to the suction side of said compressor, an oil bath associated with said compressor,.an oil circuitconnected to said oil bath and located exteriorly of said compressor, means for thermally associating said conduit means with said oil circuit.

7. The structure recited in claim 6, said oil bath having a discharge connection into said oil circuit at a relatively high level and an intake from said oil circuit into said oil bath at a relatively low level.

8. The structure recited in claim 6, and lubricant flow-forcing means in said oil circuit.

9. The process of refrigeration comprising the steps of compressing hydrocarbon refrigerant, condensing the refrigerant, evaporating refrigerant to produce cooling, passing the relatively cold refrigerant fluid discharged from the evaporator to a place of recompression, utilizing a lubricant of predetermined viscosity to aid in said compression, maintaining said lubricant at or below the temperature level above which foam formation occurs by passing the relatively cold fluid discharged from the evaporator in sufficient quantity and velocity in thermal association with .said lubricant while preventing contact between said refrigerant and said lubricant to retard and substantially prevent the formation of foam, the said predetermined viscosity of the lubricant being of such-value as to act as a proper lubricant in the aiding of said compressionafter it has passed in said thermal association.

10. In a refrigerating compression system utilizing a hydrocarbon refrigerant to produce refrigeration by evaporating said refrigerant in an evaporator zone and utilizing a lubricant oil to effect lubrication in a compressing zone, the

method of cooling said lubricating oil in heatof the oil.

exchange but not in contact with refrigerant vapors by superheating said vapors on their way from said evaporator zone to said compressing zone, superheating them substantially to the temperature of the cooled oil, to the effect of reducing by said cooling of the oil the foaming 11. The process of refrigeration comprising the steps of compressing a hydrocarbon refrigerant, utilizing a main body of lubricant to aid in the said compression, condensing the refrigerant, evaporating refrigerant to produce cooling, continuously passing a portion of lubricant from the main body thereof, passing the relatively cold fluid discharged from the evaporator in thermal association with at least a portion of said lubricant pas ed from said main body and continuously moving the cooled lubricant to said main body whereby the lubricant to be cooled is passed in a circuit-like passage between said main body and said thermal association.

PETER S'CHLUMBOHM. 

